Tuning the local frictional and electrostatic responses of nanostructured SrTiO3—surfaces by self-assembled molecular monolayers

Paradinas, Markos; Garzón, Luis; Sánchez, F.; Bachelet, Romain; Amabilino, David B.; Fontcuberta, J.; Ocal, Carmen

doi:10.1039/b924227a

Cited by 22 publications

(32 citation statements)

References 31 publications

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“…Chemical self-assembling at surfaces of ABO 3 perovskites with (001) orientation has been proposed to be a suitable technological approach for lateral surface nanostructuration [4]. It has been shown that the two distinct terminations AO and BO 2 , which are randomly distributed in as received (001) single-crystalline substrates, can be promoted to order in well-defined regions having in majority either AO or BO2 composition, differing by ½ unit cell (uc) in height (≈0.2 nm).As reported in previous scanning probe microscopy studies concerning (001)STO structuration [5,6], such regions can form either confined leaf-shaped regions at the intermediate stages of self-separation or regularly ordered arrays of stripes, some few tens of nanometers wide and several hundred microns long, once the surface reordering is fully developed. A modulated electrostatic contact potential difference (CPD) was measured at ambient conditions by Kelvin probe force microscopy (KPFM), showing a pattern that replicated the self-ordered surface topography [7].…”

Section: Introductionmentioning

confidence: 79%

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces

et al. 2015

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ABSTRACT:The (001)SrTiO 3 crystal surface can be engineered to display a self-organized pattern of wellseparated and nearly pure single-terminated SrO and TiO 2 regions by high temperature annealing in oxidizing atmosphere. By using surface sensitive techniques we have obtained evidence of such surface chemical self-structuration in as-prepared crystals and unambiguously identified the local composition. The contact surface potential at regions initially consisting of majority single terminations (SrO and TiO 2 ) is determined to be Φ(SrO) <Φ(TiO 2 ), in agreement with theoretical predictions, although the measured difference ΔΦ ≤ 100 meV is definitely smaller than theoretical predictions for ideally pure single-terminated SrO and TiO 2 surfaces. These relative values are maintained if samples are annealed in UHV up to 200 °C. Annealing in UHV at higher temperature (400 °C) preserves the surface morphology of self-assembled TiO 2 and SrO rich regions, although a non-negligible chemical intermixing is observed. The most dramatic consequence is that the surface potential contrast is reversed. It thus follows that electronic and chemical properties of (001)SrTiO 3 surfaces, widely used in oxide thin film growth, can largely vary before growth starts in a manner strongly dependent on temperature and pressure conditions. INTRODUCTIONElectronic redistributions at solid interfaces occur to reduce the chemical potential gradients, and the energy cost to bring electrons in/out across these interfaces is strongly influenced by the intrinsic properties of materials involved, namely, the work function (Φ) in metals and the electron affinity (χ) and the ionization potential (IP) in intrinsic semiconductors and insulators.The work function of metals and degenerated semiconductors depends on the electron density and surface dipoles formed at the corresponding free surface. Similarly, the IP of insulators and intrinsic semiconductors depends on the crystallographic plane considered. Modulation of the substrate work function, as required in most common planar electronic devices or active surfaces, can be achieved by changing the carrier concentration by chemical or electrostatic doping, or by chemically engineering the surface. A beautiful example is the LaAlO 3 −SrTiO 3 interface, where a high mobility two-dimensional electron gas (2DEG) can be formed only if the STO surface is TiO 2 terminated [1]. Although, following the pioneering work by Kawasaki et al. [2], TiO 2 singleterminated (001)SrTiO 3 (STO) single-crystalline surfaces can be prepared, as-received crystals display

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Section: Introductionmentioning

confidence: 79%

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces

et al. 2015

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“…The same tip was used in all the experiments of 6 at least one series. Experimental details of these measuring modes and the particular set-up employed are given in the Supplementary Data and can be found elsewhere [17][18][19][20].…”

Section: Methodsmentioning

confidence: 99%

Prominent local transport in silicon carbide composites containing in-situ synthesized three-dimensional graphene networks

Miranzo

López-Mir

Román-Manso

et al. 2016

Journal of the European Ceramic Society

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In-situ grown graphene/SiC composites developed by spark plasma sintering have emerged as a very interesting family of materials with expected high performance for advanced applications. In this work, the local functional properties of graphene/SiC ceramics are elucidated for distinct α-and β-SiC polytypes combining scanning probe microscopies. We unambiguously identify all composite constituents and demonstrate the formation of a three-dimensional graphene conductive network inside the composite. The investigated composites exhibit grains with different doping level depending on growth rate during sintering so that conduction paths associated to graphene and matrix networks may compete. The relevance of nanoscale characterization on functional graphene/semiconductor materials is proved as it evidences the type of doping and carrier concentration of the semiconductor and the critical role played by the graphene constituent in the formation of ohmic contacts. Both issues of crucial importance for understanding the macroscale behavior of these materials and determine their applications.

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“…Its inter-spacing depends on the distance to the substrate steps, in agreement with the surface diffusion mechanism proposed in ref. [22]. The expected interface, mostly LaO/TiO 2 with small and sparse regions of insulating AlO 2 /SrO clusters, is sketched in Figure 1f.…”

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confidence: 90%

Laterally confined two-dimensional electron gases in self-patterned LaAlO3/SrTiO3 interfaces

Foerster

Bachelet

Laukhin

et al. 2012

Applied Physics Letters

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A bottom-up process has been used to engineer the LaAlO 3 /SrTiO 3 interface atomic composition and locally confine the two-dimensional electron gas to lateral sizes in the order of 100 nm. This is achieved by using SrTiO 3 (001) substrate surfaces with selfpatterned chemical termination, which is replicated by the LaAlO 3 layer, resulting in a modulated LaO/TiO 2 and AlO 2 /SrO interface composition. We demonstrate the confinement of the conducting interface forming either long-range ordered nanometric stripes or isolated regions. Our results demonstrate that engineering the interface chemical termination is a suitable strategy towards nanoscale lateral confinement of two-dimensional high-mobility systems.

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Tuning the local frictional and electrostatic responses of nanostructured SrTiO3—surfaces by self-assembled molecular monolayers

Cited by 22 publications

References 31 publications

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces

Prominent local transport in silicon carbide composites containing in-situ synthesized three-dimensional graphene networks

Laterally confined two-dimensional electron gases in self-patterned LaAlO3/SrTiO3 interfaces

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Tuning the local frictional and electrostatic responses of nanostructured SrTiO3—surfaces by self-assembled molecular monolayers

Cited by 22 publications

References 31 publications

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO3 Surfaces

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO3 Surfaces

Prominent local transport in silicon carbide composites containing in-situ synthesized three-dimensional graphene networks

Laterally confined two-dimensional electron gases in self-patterned LaAlO3/SrTiO3 interfaces

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Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces

Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO₃ Surfaces